158 THE INSECT WORLD. 



with silk threads. Reaumur saw this caterpillar work and erect in 

 this way a large blade during an hour and a half. 



"When one sees," he says,* "an insect which, to construct a 

 cocoon, begins by collecting together an infinite number of small 

 plates of bark in order to compose of them two flat triangular blades ; 

 which, to gain its end, takes means that seem so roundabout, 

 although they are the most suitable and the quickest it could adopt, 

 one is very much tempted to consider such an insect, when one sees 

 it thus acting, possessed of reason." 



These two blades are at last transformed into a regular cocoon. 

 The little animal, which is at the same time architect, cabinet-maker, 

 and weaver, arranges it in such a way as to form a hollow cone, which 

 it only remains for it to shut. Reaumur calls this sort of cocoon or 

 shell, la cogue en bateau, the boat-shaped cocoon. Some caterpillars 

 weave cocoons of the same form with pure silk. 



To bring this subject to an end, we will mention the industry of 

 the Puss Moth (Dicramira vinula), and that of a small Tinea, which 

 eats the barley stored away in our granaries. 



The larva of the puss moth employs in the construction of its shell 

 the wood of the tree on which it has lived. It bites it up, and mixing 

 it with a glutinous fluid which it secretes from its mouth, reduces it to 

 a sort of paste, which it then uses in the formation of an envelope, of 

 such hardness that a knife can hardly cut into it. 



The Tinea lines the interior of a grain, of which it has previously 

 devoured the contents, with a coating of silk, and divides it thus into 

 two different chambers. In one of these it is to change into a pupa ; 

 in the other it places its excrement. And so the little careful 

 architect constructs its house in such a manner as to find in it 

 tranquillity, cleanliness, and comfort. 



When caterpillars have not within their reach the materials they 

 are in the habit of employing, like good workmen, they content them- 

 selves with what they can get. Re'aumur reared a caterpillar which 

 formed its cocoon of pieces of the paper of which the box was made 

 in which it was imprisoned. 



What an extraordinary condition ! what a strange phase of vitality 

 does the chrysalis present to us a being occupying the middle state 

 between the caterpillar and the perfect insect ! How little does it 

 resemble that which it previously was, and what it will become ! In 

 appearance it is scarcely a living being ; it takes no nourishment, and 

 has no digestive organs ; can neither walk nor drag itself along, and 



* Mem. 12, vol. i., p. 487. 



